A 42-year-old HIV patient with leukemia appears to have no detectable HIV in his blood and no symptoms after a stem cell transplant from a donor carrying a gene mutation that confers natural resistance to the virus that causes AIDS, according to a report published Wednesday in the New England Journal of Medicine.

"The patient is fine," said Dr. Gero Hutter of Charite Universitatsmedizin Berlin in Germany. "Today, two years after his transplantation, he is still without any signs of HIV disease and without antiretroviral medication."

The case was first reported in November, and the new report is the first official publication of the case in a medical journal. Hutter and a team of medical professionals performed the stem cell transplant on the patient, an American living in Germany, to treat the man's leukemia, not the HIV itself.

However, the team deliberately chose a compatible donor who has a naturally occurring gene mutation that confers resistance to HIV. The mutation cripples a receptor known as CCR5, which is normally found on the surface of T cells, the type of immune system cells attacked by HIV.

The mutation is known as CCR5 delta32 and is found in 1 percent to 3 percent of white populations of European descent.

While promising, the treatment is unlikely to help the vast majority of people infected with HIV, said Dr. Jay Levy, a professor at the University of California San Francisco, who wrote an editorial accompanying the study. A stem cell transplant is too extreme and too dangerous to be used as a routine treatment, he said.

Levy also said it's unlikely that the transplant truly cured the patient in this study. HIV can infect many other types of cells and may be hiding out in the patient's body to resurface at a later time, he said. "

HIV is notorious for its ability to mutate and evade drugs designed to destroy it. Now scientists are testing a new drug that actually speeds up that rate of change in the hope that the deadly virus will mutate itself to death.

"The HIV virus is so dependent on mutation that it really lives on the edge of existence," said John Reno, Chief Operating Officer for Koronis Pharmaceuticals, the company developing a drug called KP-1461. "But we figured that if we could increase this mutation rate, [HIV] might finally fall off that edge."

KP-1461 is a mutagen, meaning it encourages mutation, and has been in development for several years by the scientists at Koronis Pharmaceuticals. KP-1461 looks like both thymine and cytosine, and will occasionally replace one of the normal bases in DNA, causing more errors.

The results of the latest Phase Two clinical trial, completed last year with 13 patients, were mixed; some patients saw no drop in their viral load, while others saw a dramatic drop. The scientists are currently working to publish the study results.

Mutagenic drugs could be used to fight other diseases as well, such as polio, hepatitis C and influenza. KP-1461 is at the forefront of this new avenue of research. "